Blender growing polygons
There are many ways you could achieve "build" effect. The simplest one that mimic the Build Modifier, but does not simply "pop" the polygon faces are of course by using Add-Ons like Animation Nodes. 

You could probably use Blender's own Particles as well to kind of reveal each polygon face slowly one by one?

One idea, using Animation Nodes Add-Ons:
1) Install Animation Nodes (AN) Add Ons.
2) Study a little bit a bout AN. Get a hang of it.
3) One of the Template provided to transform individual polygons will be perfect. The idea here is instead of appearing like a sudden pop, you want to use some kind of transition. The most obvious is probably to animate scaling of each polygon.
4) With a little adjustment you can get a more elegant "reveal" of your 3D model, perhaps in this case is basically polygon by polygon, as they are scaling from Scale zero to one.



Remember the way it is being revealed is also important and there are limitless way you could do this from basics to more sophisticated effects.

Here is basic: